Venus flytraps are the most popular type of carnivorous plants, but you have to be pretty far South to grow those outside. I have found some pitcher plants and sundews that are suitable clear up into zone 2, both of which have brilliant reds and greens. Both of these tend to grow in peat bogs, so they prefer acidic soil/water. This is actually ideal for me, because my pond is beside a row of blue spruce pines, so a lot of needles and pine cones get in the water, keeping my pH lower than normal. Once I have a suitable area for them, I plan on getting some of each plant to grow. I think they'll really add a unique look to those areas of my pond!
http://en.wikipedia....wiki/Sarracenia
http://en.wikipedia.org/wiki/Drosera
[EDIT] Sarracenia purpurea is the pitcher plant you would want, however one caveat is that I have not had much luck finding live plants for sale. You can find lots of seeds for a very low price, but these plants take 4-5 years to mature. I guess its one of those things you have to plant early so you can enjoy it later down the road, but then again raising the plant from seed means they will be well-suited to your specific conditions.
http://en.wikipedia....wiki/Sarracenia
http://en.wikipedia.org/wiki/Drosera
[EDIT] Sarracenia purpurea is the pitcher plant you would want, however one caveat is that I have not had much luck finding live plants for sale. You can find lots of seeds for a very low price, but these plants take 4-5 years to mature. I guess its one of those things you have to plant early so you can enjoy it later down the road, but then again raising the plant from seed means they will be well-suited to your specific conditions.